PhilipG,
Many of the ex-military aircraft flying in the USA are registered in the Experimental category and are not required to operate with functioning ejection seats, although some may be eligible to do so and the requirements are stated here:
Experimental Airworthiness Certificates
Examples of Experimental registration:
Draken:
Platinum Fighter Sales | Warbird and Classic Aircraft For Sale
Mig 29:
Mig 29UB / Fulcrum B by Raptor Aviation, Inc.
For those that are interested, the FAA pilot qualification requirements are here:
http://fsims.faa.gov/wdocs/8900.1/v0...09_002rev1.htm